In general, an excavator is a construction machine for performing operations of digging the ground, loading the soil, transporting the soil, and unloading the soil at construction sites. FIG. 1 is a view illustrating a general excavator. The excavator includes a lower traveling body 1 which supports the excavator and allows the excavator to travel, an upper turning body 2 which is provided with a cabin 3 and supports working units, and the working units which include a boom 5, an arm 6, and a bucket 7 and perform various operations. The boom 5, the arm 6, and the bucket 7 are pivotally coupled to the upper turning body 2, the boom 5, and the arm 6, respectively. The boom 5, the arm 6, and the bucket 7 are operated by a boom cylinder 8, an arm cylinder 9, and a bucket cylinder 10, respectively.
The working units such as the boom 5, the arm 6, and the bucket 7 are operated by an operation of a joystick. The user may individually control the working units by operating the joystick. In general, an operating speed of the working unit is in proportion to an operation amount of the joystick. That is, the working unit operates at a low speed when the operation amount of the joystick is small, but the working unit operates at a high speed when the operation amount of the joystick is large.
However, a working tendency varies in accordance with users, and as a result, assuming that the working unit is operated by operating the joystick with the same operation amount, some users may think that the operating speed of the working unit is low, and other users may think that the operating speed of the working unit is high.